The invention relates generally to rotary cutters for cutting web or sheet material, and more particularly to a knife holder apparatus which may be attached to a knife cylinder and employed with an associated anvil cylinder to transversely cut or score a moving web or sheet.
It is conventional practice to use a rotary cutter to transversely cut web material received from a printing press. In general, rotary cutters have an anvil cylinder and a knife cylinder which are rotatable in timed relation. One or more knife holders, which hold the cutting knives are attached to the knife cylinder. The knife and anvil cylinders normally rotate at the same speed and the moving paper or web material is transversely cut or scored as the cutting knife moves into and out of engagement with the anvil surface. The cutting knives may be spaced apart to create the desired cut.
In the conventional rotary cutter, knife replacement is a time-consuming operation. Reducing this replacement operation has become even more important with the increased use of recycled paper and its negative effect on the life of the cutting knife. To reduce down time due to blade replacement, unitary epoxy knife holder and blade assemblies 112, for example, as shown in FIG. 14 have been employed. Replacement of a worn cutting knife, however, requires that the entire assembly be removed from the knife cylinder, which requires stripping away the cushioning and rubber material which is placed over the knife cylinder and portions of the holder. The installer must then realign and remount the replacement holder on the knife cylinder. This problem is partially avoided by use of a knife holder assembly as shown in FIG. 15. This knife holder assembly includes a metal holder 116 and a backing member 110, which locks a cutting rule 114 to the holder 116 with holding screws 118. Although this knife holder assembly does not require the complete removal of the holder 116 from the knife cylinder, it does require some of the cushioning material to be stripped back because the release screws 118 are located on the side of the holder. This requires the person changing the cutting rule 114 to loosen the holding screws 118 from the side of the holder, which is both awkward and time consuming.
It would be desirable to have a knife holder assembly that would allow the user to quickly and efficiently remove the worn cutting knife and replace it without removing the holder from the knife cylinder. It would further be desirable to provide a knife holder assembly that would aid in relieving some of the wear on the knife blade.